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Of all places, Paris! In 2012, while writing a book on the Hemiptera order of insects – it includes aphids, cicadas and others – I made a new discovery, and an unwelcome one: a new invasive species in the heart of the French capital, in the Jardin des Plantes.

Halyomorpha halys is a large (up to 1.7 cm) grey Pentatomid – known colloquially as stink bugs. Originally from China, Korea and Japan, they began to invade the world about 20 years ago, travelling thanks to human activities. The standard English-language name for Halyomorpha halys is the brown marmorated stink bug (BMSB), but in France it has also been called the “punaise diabolique” – the diabolical or devil bug – because of its impressive size, fondness for large-scale gatherings and seriousness as an agricultural pest.

Since September 2016, I have detected its presence in several other Parisian gardens in a larval state, meaning that it is reproducing. This is a silent invasion, despite the insect’s large size and lack of discretion in the fall, when it seeks to enter homes. It is this behaviour that has given the nickname of “evil”: By September 2017, it had become a serious problem in France, with some residents reporting swarms of bugs essentially knocking on windows seeking to enter homes and apartments.

No decision has yet been made over how to manage of the species, or even how to study it (for example, urban ecology…). Parisians are just helpless spectators of this silent invasion. In any case, Halyomorpha halys is impossible to confuse with his cousin, the bedbug Cimex lectularius, which is “diabolical” in other ways, particularly its fondness for human blood.

Storming the world

The “devil bug” arrived in the United States in 1998, and today has been spotted in 41 states as well as Canada. It’s “polyphagous”, meaning that it is able and willing to attack a wide range of plants – more than 120 so far, including a large number of cultivated and ornamental species. It attacks all parts of the plant and causes serious damage to fruit. In the Eastern US it destroys fruits such as peaches, apples and pears as well as vegetables like tomatoes and peppers.

It was Europe’s turn in 2010, when the “punaise diabolique” was first spotted in Switzerland. Since 2012, it has been sighted in several other countries, including Italy, Greece and Hungary. It begins to appear in southern and western France in the summer of 2015. Particularly at risk in France are hazelnut orchards – and it’s just one of the crops at risk. Studies analysing yet-uninfested habitats where this species could prosper show enormous potential throughout France and the world.

Big city, bad bug

One of the characteristics of Halyomorpha halys is its appreciation of urban areas and, in winter, the shelters it provides. Gardens are lovely when the weather is good, of course, but with the arrival of colder temperatures, the insect seeks refuge in houses and buildings, sometimes en masse. While it is fortunately harmless, disturbing images and videos are everywhere.

Ways are being developed to fight against the insect, including the use of pheromones to attract them and biological-control programs using parasitoids. In France, the national food safety agency, ANSES, has issued recommendations, while the French national agronomic institute, INRA, has launched a participatory detection program. The National Inventory of Natural Heritage and the National Museum of Natural History (INPN/MNHN) are also seeking the public’s assistance. Initiatives include using citizen-scientists to search gardens, parks and structures to look for larvae and adults.

While procrastinating, the invasion continues

Beyond the wealth of online videos, however, there has been relatively little publicity about the invasion of the brown marmorated stink bug. Even if it is not possible to act directly, vigilance and information must be in place, as highlighted in the ANSES report. In Europe, so far Italy leads the way: The country launched a participatory survey in 2013, and two gatherings of scientists and agronomists dedicated to better understanding this species took place in 2015. The Journal of Pest Science published a special issue focusing on the “devil bug” in 2017.

Other European nations do not seem to be taking the as seriously as Italy is. An invasive species is one that extends its range relatively abruptly, and because they often don’t have natural predators in their new environments, can even replace local species. In the absence of an action plan – eradication or control, which can be difficult to implement – information gathering is the best solution. It involves vigilance and, where possible, anticipation of potential nuisances. Above all, it helps to avoid bad decisions: incorrect identifications, untimely pesticide treatments, management errors in urban ecology or agroecology, etc.

Without information and detection, it’s difficult to know the true distribution of these “aliens”. Whether or not a species is invasive is not always simple to determine, at it can also be influenced by environmental factors such as climate change:

Halyomorpha halys, possibly coming to a garden near you.Author provided

The story of the “devil bug” is one of natural history and taxonomy in the world in which we live. Learning more about the creatures around us, native or not, in the countryside or the city, is essential. It’s essential to remain vigilant, to recognise species of medical or agronomic interest – it’s our biosecurity, after all. While strictly molecular approaches are all the rage, where biologists spend more time in front of their screens than in the field, let’s not abandon taxonomy and systematic exploration of the environment that so many of us live in, cities.